SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '638246522d0bbebc63877841d08b49ebdb67f1e8ff35fb2d25ccd10afe13756e' 
  AND token = 'Qr+8ZF88qi8xcHoJ65HxGXG8kQGUccrdMVHTQugoXnk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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