SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '80df3a999580a75b3074764012feb7f2cca1a2c84f9703af6099bad776ea8803' 
  AND token = 'NC4mDIGE6QjPT3ervG+2xw2HHMcUZfrY/xDpALCpcP0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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