SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d2f466725d9e50c33dae101795c57a3cd550062693194ebf11abe8d34161210' 
  AND token = 'g5WYh0kuXfOcUPlaFhyNteWqAxxiVNU9pM+x9IUv+Ac=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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