SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b77156ea07a17127f245b5cd9b10745b1583aa121f25682613167da3243934b' 
  AND token = 'KEaDfm543jn/Kh7XdB+zIz8S4N1GLNZ3+TU4Hu3TIyE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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