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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b06f6e2865cd283e8f421f3a664e66febd2dd35bb31386833fb3f22d8d5c0305' 
  AND token = 'oDutLM2ejJ+OgOFlWxVfUZRhetf1hUDhMoD7Hr1XAi0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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