SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cad5f29187b9ea6d232a1b405ebcef3a7a4ad70afb627afe2d82c5e6421f1ec8' 
  AND token = 'ejmG8pWIIax0UPN855bnnawqAyALy+LKrJnnFKutK4s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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