SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e849d525fc14c0f8d1491457259ba95950ca1f5ee72e666b52be5285bfa1d489' 
  AND token = 'UJ+ITlTxybsfucBeOioMP5E3sNlhglYvD+obD/spThY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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