SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8d0742884cf3b80d4e01328b02592888df8228c63bd6e229ae7e9d118276e12' 
  AND token = 'h3DL0/EbMTtueQXuPQBLvrfGj1V6tJfG/cK/KlAD+Bw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00054

JSON explain

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