SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ea46c7273cd094ec011c26f5b0a03d1fcb87d412efea75431be0d36b9e9267c5' 
  AND token = 'EJdm0O57UedVRk4f3PvfWbv72vS4aTRat3EzGjM+d88=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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