SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a21455455d350023cb7b412b296b12a7a2aeb8cf0778d6dcbf5df2d8f041c8d1' 
  AND token = 'IkRbzYZt62jl6++jEt+5K7yfFXY5lwCBtDSUcKU2dwY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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