SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f252a1a5360c75d30da95a0b078db81cd87fb8ff458b922216091fe388c5ded5' 
  AND token = 'wqYrsd/ZOT3lrv+siJCdKnZ/X8vkmdCVnb5rNY65C/E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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