SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f449210458e56e4c091c7512e0745e5ad896db072f43557752770c678f648c2' 
  AND token = 'n5T/i/rrUvCpLtqEEtTWkrkNbHqlEn5zMrnXSFAI0ZU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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