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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df97d9d925f38852eb5ef1875d464c7670e0fdfa1a0d99c25f240da9e6a57552' 
  AND token = 'DXyjaUS0Y33cyOm6COrauVbCnndAM3ETPyHsdn4/ZjQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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