SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'db8e00b26415d9bb188ff782a34f248e4b7616bf8ed76af911068e8fb65d0d10' 
  AND token = 'aifLV9kApF7qtjJowF1UYW9jnB1vhms/VunkB3ZViQc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00058

JSON explain

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