SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '587af486937718ee9665991240a844eee55ac2d03d69bc7ba441aa2f57022d42' 
  AND token = 'NUjkI/KG8dArvJbxN5ePmpf0fP7j967NvU2vSbeFl8o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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