SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '425b75a0718167c7ad4556e7dbe5052d3a79029a46f3dd574a7428837e53635a' 
  AND token = 'VjGSZBCynCMRaRdYH+SCetomfsgsvcjyTmVu7LY/Ss4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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