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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '55d4bb501ddc3599c93bf31d042fd9574ac6c44cdf85b729ccff1a88dce75086' 
  AND token = 'MZzD7Fv5Tbmvi911Eh6QM9DT82cR+0hJYhvoeoa6y+4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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