SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b06d326392010fd075067139e2e3b58ef6cc1b512a1ab627e489fe60f3d55ff' 
  AND token = 'r6YJWem4RLZXZL5FvFhZHArMVrqpWUvxhUQERUH+2mo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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