SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2516a2c636cff6682793f4a0992590ec4bf5cd762d15b31210b2bc1d3ff054a4' 
  AND token = 'wB8p51oXvlw9k5QY0jsjKqQnhM5rnlJv/Y5DgRWkvB8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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