SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6fb75daef3a2a14a086fa0b85c5b610f5d912b3b3beece61c4d97d396ff1edb2' 
  AND token = 'X1WHjfxYFq89h7w/O3asZvi6+Ny7EaVBTyf54ZCzzT8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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