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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd71aab4efb8c21b184beb246f597644fd3aadbbbe07d41f1ffd53c477c655df4' 
  AND token = 'Rhnq46XLu1xUgnj+sZLI6KNUEea/YmEHprVf5jbxtHg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}