SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0b61dd0b17ac32ca3ba252972a67488d7aa4157d01b718d429e609afcc56df8c' 
  AND token = 'iUrMmN0c2Hu+NwIUZtZgWYgZKcp8roUgHYeta5abQhM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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