SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a3547331d79e9f14f291282cacb1a602e04dd060801eceb26df14de0ff9791e7' 
  AND token = '7i+IKnmrYrM3ex2dJvX/f9CA6KjCwhETFaetAyv+47Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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