SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3d247aa990afbeea7f18eccd8cc9510da65b618cf4a84f9803ba2b58078baa4' 
  AND token = 'eBPwXrOTGq9KGv/Dj/ku2Z6+xeMNcgrLN6+gjVJjJYA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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