SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50d7fd4d7323a71ee7d150492a0bb587bde8def97790d0a1258003bf0808b8f1' 
  AND token = 'KMdILF9R/vUlSHIaWUcG+fWExEoapQ0pCHS+C2qAavM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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