SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '78cae58d425893be6eccc266e3a0ab4c7021dd4c69d0744b910265585732722c' 
  AND token = 'fYmaYqohTWkKo00+2yjB4SPRrvSxhW3rokhTjNSzqZw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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