SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fe7c331ca74ea87fb01751ba6b133ae5d368c842421289d6027ddc54be1aa647' 
  AND token = 'd6fyskQ8U8SkROnCoV2N6mgQnj9PfijKsR0e8qUYXIc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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