SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '1688b8bb6188b1e5c5d66f4fecbbc10e733277ef5c2e7afed2d0ad2e5e10d518' 
  AND token = 'KGLCjPLfaLzmhw9zNz2lvx0MjZhnImCRjghcHbYMWt4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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