SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cb6349e0466744872ac12fddcd2508d9083189796795e56a97fa393964d7dc65' 
  AND token = 'IZRyONeYGY/LjV0gCJGFJycqXCrl6b2fijm+RBSoTls=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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