SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e31874109658cd7b52da5f9a15bfff0dbad44fecb4be05a751b6594c158f1268' 
  AND token = 'a3IutQZy71YXfj7wpylTjc37n9YJkYOqkCKBmqrzBOc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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