SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50ae519f840f7c93353b163691839db470610c8eb227c4363c0bfe2d91e416be' 
  AND token = 'jQ6isZKDe6bir4NB30PbsWwtcKvRttmXxp/283E0t4k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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