SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75d93a93af76b871a4fa3bce6741f5ebaeac84f53cbddb188078df644f6fb111' 
  AND token = '1kBSvf9s8zI48bA8KaV6BYMAQ429XyO87CJWrNV7X+g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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