SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7b7b6202526720b0feed59184bcb2737e35525f70a0bc598855b2ff7d1c2ec3a' 
  AND token = 'PsUzv6d1SIPXGy5PINAL2rqRpYIjlgO69l0DSkgnQfI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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