SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a4f5288a0ea037eab953eb4fe898b4d70f4d4255b147835b69f372f742000860' 
  AND token = 'iCwL+iUpO2LPl72PXo1gximIxCkxZyKL2q/BfW7nvzI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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