SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '426d94da3f9629059e15df8e97b0be957289f21ac8f87b1c2f9be40557007e2d' 
  AND token = 'ffpmLPRp9kenB/2zZ+fgnuw3rZFIMYhwemYQWIwfYYI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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