SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '49e6925ca83163510d1b10eca7f9f9b792f7911f048125a33bbfecd76f493694' 
  AND token = 'CWL6pRVeNmGDCSmSdlYC+nuCrXg712HQPga5LzRNg7I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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