SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9873c084f9ab6c843d7ffdfa100c1ba83478ed617fe11fc22f360d841be14a21' 
  AND token = 'Q2lGMYhcfLuJG5qKLjOot/mhazbC21GCTGYtveziQPU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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