SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '818ac22d65305d406c92a347a181107305b80903ef4b04a9010d95d9ef2e307a' 
  AND token = 'crQKlC2W1ImkficPE8fEOSq7tF61YErCpIAOh53V3qs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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