SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15aecd33ee63e389d50ca9b9d4db6a627192b4e4fa0046ad9535d715f01ec2f4' 
  AND token = 'e1Z+wGz+fV8ndXKWUP6Jljv8EuGAKi+NpL4+Xt/DAnc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00013

JSON explain

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