SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '337a31bc0e383057ff2c45c4e694aec6e8139467daea589154c1c380cfab2541' 
  AND token = '7lrOJwa0AAwc94BVeoa60NugkXjAElnN1lGLBxHrc4Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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