SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3a2a054593537c890525eb05a4d7cd9ec0b72f27dc24dbceefe71e70d1dbd6b' 
  AND token = 'lMoeLDqVWil5nHEBk7GfPijbMpMi08R5nKQZW/20coU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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