SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b765401883560d54dbfe91892b7314d2fdb1ed15dde910c403780b3a63aa4ae' 
  AND token = '5GKVgQ+Omli4iKoq7D9PrBrA+IK/1hXSNr5Rj/aB2gI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}