SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b85ca478f5141a9b8a2ecf311aa1c20d2d7ce75ba95bb752a198076b6748bb63' 
  AND token = 'mqwZuwCuKsN1BvfRVTUdzm+Mof9Z5rHEJDPf/jQMHPE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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