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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5b8eceb35b1b8d953f14734fdbfca74568e1b764c85839818d76f949f8ba2cd2' 
  AND token = 'u2bGtCFxXlQ5MbY3Bn+HD7fOA6/F+FS79i+J5aI6hSM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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