SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a556e16fc718eb963ce87f2f5883e4b184b382d219cd6e5293f9b92879a9ed1e' 
  AND token = 'YWGE/yhi+rG4L1y3ADdbRQ0hw7VZRlrzaByFEomq5LI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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