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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd3b39fa2c4bc14097e1140b78f00ce10783fde9ca45bc2d18b7140bbdab51ed5' 
  AND token = 'c+jzIWclfOs1MTWkozIYuXwqsR8mwiW37kVgVUeqFdc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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