SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a3a842f953e7eca0124ccfedef81cdf72494c1175c70e9580ff88fdc34815879' 
  AND token = 'FZcv6bpwU7b3ALRDod16LgLqImreh1ZsZPiXM1emrvU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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