SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fc3be22af081412282f61901e39b08963722b855f0221382fd12e3fddfe23b00' 
  AND token = 'eIKFib5q1UAABBgfIg9J97VjjKSZsIlXNBEkrWcNJt4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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