SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fd8fd5604c87a0103bfad011ab58e4f6295e5cdd7fa1262e63bee835be3eb3f3' 
  AND token = 'laZznl/RorZf+/3y+t3guvrGLkTHAVvFoa/fd1bcio4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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