SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f00e19ec53ce40adac566389fc821463b14d4661f7bd08528221790115633c9e' 
  AND token = 'mr7vfvhukEptnVsVM1aZg3i75uUdG+7cdTTaYYF1tO0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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