SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '48b74000aeb675f6ef87ac5fdff5784033d1026611305eaae43c9f82e2d16afb' 
  AND token = 'mX+SDgDmkhN84K/RMAzQt9uKqnXrV+xmpiGOOOTz/Qg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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