SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '37dee20955372ca22964f82398290333dc491fb1f891d09a2e58b20147ca13fe' 
  AND token = '/hU4OfRugp28Pny3hWs/syBWw65MaPncAbdgZdZqtsY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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