SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '64ac479de0b5f456555ad018e3a8ff7e51aca30e652c45cbfcc6039408899d82' 
  AND token = '2jR4sNKwZp2cnR67kgodL0mrFapnEIBZJWACmA9BQRU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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