SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a646291d5c430678244d54011ff2f1383e40d20a47207255d8963eca76a93c13' 
  AND token = 'PMHl/j5JIRsRhzMXm9pdruepg2azoekRMXUXltOr75I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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