SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a0b798250bfc0cce8e1c18f8bb5cbda31299dd3704ff50397b09ee81cc64d7e7' 
  AND token = 'nWEEqhmWcEQLJlgb5g6rZ0RrhFpmo8MCaG/RL7VpCmU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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