SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '968810efdf98d6cb008aed4c1f520690debf940d5d037c13993942104ad383f6' 
  AND token = 'rJCSAUpPz0cTpfUR+39BKBO9EG0naRNOjCEyIupgtDk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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